@article{ERMS:SourceID:277941, author = {Ratzel, Fritz}, journal = {Zeitschrift für wissenschaftliche Zoologie}, note = {although printed in 1868, the fourth part (with this Ratzel paper) was issued on February 1, 1869}, title = {Beiträge zur Anatomischen und systematischen kenntnis der Oligochaeten}, url = {https://www.biodiversitylibrary.org/page/45035091}, year = {1869} }